Boiler and superheater



6 Sheets-Sheet l Feb. 17, 1942. E. L. SCHELLENS ET AL BOILER ANDSUPERHEATER Filed March 1'7, 1959 Feb. 17, 1942.

E. L. SCHELLENS ET AL BOILERA'ND SUPERHEATER Filed March 1'7, 6Sheets-Sheet 2 Feb. 17, 1942. E. SCHELLENS-ETAL BOILER AND SUPERHEATER 6Sheets-Sheet 3 Filed March 17, 1939.

00 0 0w0m W 0 0 M 9 0 0 0 m 0 0 0 0 W 0 0 0 0 0 M 0 0 0 0 O O 0u0% 0 0 00 0 N O 0 0 W 0 0 0 W0 0 0 0 0 0n 0 0 u 0 0 0 0 0 0 C 6 O G O O O 0 O. 00 0 0 00 0 0 0 u 0 0 0 0 0 m H O 0 0 1 0 0 0 O E. L. SCHELLENS ET ALBOILER AND SUPERHEATER 6 Sheets-Sheet 4 Filed March 17, 1959 Feb. 17,1942.

Ifiverrtors.

E. L. SCHELLENS ET AL 2,273,290

BOILER AND SUPERHEATER Feb. 17, 1942.

s W n w m 'I II Patented Feb. 17, 1942 UNITE STATES PATENT OFFICE BOILERAND SUPERHEA'IER Application March 17, 1939, Serial No. 262,440

6 Claims.

This invention relates to boilers, especially locomotive boilers and tosuperheaters, especially of the type wherein a portion of the length ofthe usual fire tubes or fiues extends through a compartment in the waterspace of the boiler but from which the water is excluded and throughwhich stem is circulated to be superheated by the heat of the fiues.

Objects of the present invention include a boiler and superheater of thetype set forth wherein the superheater compartment is supported mainlyby the boiler shell; wherein the fiues within the compartment areprotected in an improved manner from the radiant heat of the fire;wherein the steam flows in a progressive and efficient manner in contactwith the superheating fiues; wherein the pressure difference between theinterior and exterior of the compartment is small and practicallyindependent of the operation of the locomotive; and wherein provision ismade for improved means for leading steam to and fro-m the compartment.

A further object 'of the invention is generally to improve theconstruction of boilers and superheaters of the type set forth.

Fig. l is a longitudinal sectional elevation through the rear part of alocomotive boiler embodying the present invention.

Fig. la. is a continuation of the section of Fig. 1 showing the frontpart of the locomotive boiler.

Fig. 2 is a transverse section through the boiler and superheater, takenalong line 2--2 of Fig. 1.

Fig. 3 is a partial longitudinal section through a locomotive boilerillustrating a different form of superheater.

Fig. 4 is an enlarged transverse section of the superheater and boilershell taken along line 4-4 of Fig. 3.

Fig. 5 is a sectional detail taken along line 5-5 of Fig. l.

Fig. 5a is a sectional detail taken along line .5a-5a of Fig. 4 andillustrating particularly the manner of securing a vertical partitionplate to the superheater shell.

Fig. 6 is a longitudinal sectional elevation, partly broken away, of alocomotive boiler showing a further modified form of superheater.

Fig. '7 is a transverse sectional elevation of the locomotive boiler andsuperheater, taken along line 'l-'| of Fig. 6.

Fig. 8 is a sectional detail of a saturated steam passage taken alongline 8-8 of Fig. 7.

Fig. 9 is a partial longitudinal section through a locomotive boilerillustrating a further modified form of the invention.

Fig. 10 is a transverse section taken along line lfl-I0 of Fi 9.

Fig. 11 is a sectional detail taken along line HIl of Fig. 10.

Fig; 12 is an enlarged sectional detail taken along line l2-l2 of Fig.10.

In the construction illustrated in Figs. 1, 1a, and 2, as applied to alocomotive boiler to which the invention is more particularly intended,the boiler comprises the boiler shell ID, the rear tube sheet 12, whichis set back or rearwardly of the throat M, the fire box I6 with itssiphons or water legs l8 located in the rear of the rear tube sheet, thefront tube sheet 20, the smoke box 22 with its steam draft nozzle 24,stack 26, and a plurality of straight fire tubes 28 extended between andfixed in the front and rear tube sheets.

The boiler shell I0 is surmounted by a smaller diameter shell 30 whichis approximately coextensive with the length of the boiler shell. Thetwo shells are open at their confronting parts and are secured togetherby being welded or otherwise fixed to an interposed tie plate 32 whichextends across the openings of both shells and connects them together inthe manner and for the purpose disclosed and claimed in our copendingapplication Serial No. 51,616, filed November 26, 1935.

Said tie plate is formed with a plurality of steam passages 34therethrough so that the steam can pass from the upper part of theboiler shell ID into the upper shell 30 which constitutes the majorsteam space of the boiler. With this arrangement the shell 30 can havean exceptionally high water level therein and have a large number offire tubes. This construction is particularly advantageous with highspeed locomotives where the tendency is to increase the diameter of thedrivers to a point where the possible boiler shell diameter is reducedto a dimension where the gas area through the fire tubes is notsufiicient for the requisite boiler power. With the describedconstruction substantially the whole front tube sheet is available fortubes, whereas, in conventional practice about one-third of the upperportion is reserved for steam space. By the use of the upper shell 30the volume of steam space is greatly raised and the number of tubes isgreatly increased by carrying the upper shell to the clearance limit andutilizing substantially the full tube sheet area for tubes and carryingthe water level above the top of the tube bank and close to the top ofthe boiler shell. As stated above the rear tube sheet IE is back of thethroat M. The rear tube sheet is provided with a lower drop portion 36confronting and spaced from a similar drop portion 38 of the boilershell to form a water leg into which the lower ends of the siphons open.The fire tubes 28 are pitched or sloped downwardly from the front to theback. The rear tube sheet and furnace crown sheet 40 is located closeunder the top of the boiler shell, and under the water level, the firebox wrapper sheet 42 being carried upwardly to about the top clearanceline or close to the line of the top of the steam shell 30. Thisarrangement utilizes the increased tube space and Water level inincreasing the steaming capacity of the boiler. The steam space underthe wrapper sheet and above the water level over the crown sheetcommunicates with the steam shell 36 through a passage 44 in the end ofthe steam shell.

The superheater 45 in accordance with this invention is located withinthe boiler shell I!) close to the rear tube sheet [2 and remote from thefront tube sheet 20 and encloses a large number of fire tubes 25. Thesuperheater includes front and rear superheater tube sheets 46 and 48,respectively, suitably spaced apart lengthwise of the tubes to provide asufficient extent of tube length within the superheater for the purposeof superheating the steam. The tube sheets 46 and 48 are perforated inconformity with the tube layout and the fire tubes pass through thesesheets and are rolled or otherwise arranged in steam tight engagementtherewith. As will be explained more fully hereinafter there is butsmall pressure difference within and without the superheater so that thesteam pressure tending to cause leakage of steam between the tubes andsuperheater tube sheets is small.

The superheater tube sheets extend transversely of the boiler shell intoedgewise contact with the inner face of the boiler shell and are weldedin a steam tight manner thereto. The locomotive shell l thus alsoconstitutes a part of the superheater shell. The superheater tube sheetsare terminated preferably in a straight line above the tube collectionbut under the water level and are welded to a top sheet 50 which also iswelded to the boiler shell and forms a top closure for the superheater.The bottom edges of the superheater tube sheets are also terminatedpreferably in straight lines transversely of the bottom of the boilershell and are welded to a bottom sheet 52 which sheet is also welded tothe boiler shell and constitutes the bottom closure of the superheater.

The space 54 under the bottom closure plate 52 and above the bottom ofthe boiler shell contains fire tubes 28 and constitutes a water passageconnecting the water spaces 55, 57 on opposite sides of the superheaterby which a directed circulation of water lengthwise of the boiler iseffected.

The interior of the superheater shell is divided into left and righthand transverse compartments 56, 58, see Fig. 2, by a vertical partitionsheet or plate 60, the upper and lower horizontal edges of which arewelded to the upper and lower closure plates 58, 52, the vertical edgespreferably being free from attachment to the front and rear sheetsalthough close thereto so as to permit free expansion of the fire tubes.While steam can leak around the unattached edge of the partition sheetthe leakage will be small since the pressure difference in the twocompartments 56, 58 is low. The plate 60 can, however, be welded to thetube sheets where, as here illustrated, tubes near the plate have beenomitted so that expansion of the other tubes is not hindered by thewelded plate 66.

The superheated steam issues from the top of the right hand compartment58 through a vertical pipe 62 fixed to the top shell plate 56 andpassing through the tie plate 32 and communicating with a superheatedsteam pipe 64 which is located centrally within the steam shell 36 andextends forwardly through the front end of the shell where it opens intoa superheated steam throttle valve 66 from which the steam can flow inany suitable manner not herein shown to the locomotive cylinders.

Saturated steam from the steam shell 30 enters the top part of the lefthand superheater compartment 56 by means of a tube 68 opening throughthe rear part of the superheater top plate 50 and through the left handside of the aforesaid tie plate 32 where it communicates with a chamberill formed by end plates 12 and T4 and an arcuate side plate l6 whichpartially surrounds but is spaced from the superheated steam pipe 64 andhas its bottom edge welded to the tie plate 32 along the middle linethereof. The upper edge of the plate 76 is spaced below the top of thesteam shell 36 and provides a long entrance slot or opening '56 throughwhich saturated steam in the steam shell can enter the compartment i5and pass into the superheater. The steam openings 34 through the tieplate confronting the plate 16 are located in th right hand side of theplate when viewed from Fig. 2 so that the steam in the boiler shell isconstrained to pass into the steam shell and thence into the compartment12 through th slot 78. This arrangement tends to separate water out ofthe saturated steam before passing into the superheater and an inclinedbaffle plate 80 is located in front of the slot 16 for the same purpose.

The compartment 56 of the superheater is formed into a plurality ofsuperposed steam flow passages by the vertically spaced horizontalpartition plates 82, S4, 86 and 88 which plates are welded to the boilershell and to the vertical partition plate 66. The plates 82, 86 areterminated close to the rear tube sheet 48 to form a closure therewithbut preferably are not rigid therewith and are spaced from the fronttube sheet 46 to provide steam passages therebetween. The plates 84, 88on the other hand at their ends are terminated close to the front sheet46 and are spaced from the rear sheet 48 for the same purpose. Thisarrangement causes the incoming steam to fiow horizontally lengthwise ofthe fire tubes and alternately with and against the directions of theflow of the combustion gases in the tubes and progressively downward.The superheater compartment 58 is divided into similar fiow passages bypartition plates 96, 92, 94 and 96 arranged similarly to the aforesaidpartition plates except that the plates 96, 94 are spaced from the reartube sheet 48 and the plates 92, 96 are spaced from the front tube sheet45. The vertical partition plate 66 is provided with a series ofopenings 98 located throughout the longitudinal length of the sheet sothat the steam can fiow transversely of the boiler shell and the firetubes from the lowermost part of the compartment 56 under the plate 88to the lowermost part of the compartment 58 under the partition plate96. In its fiow in intimate heating contact with the fire tubes theinitially saturated steam becomes highly superheated to a temperatureclosely approximating the temperature of the fire tubes within thesuperheater.

In the modification illustrated in Figs. 3, 4, 5, and a, the locomotiveboiler is provided with a cylindrical boiler shell Illa and the usualfront and rear tube sheets of which the rear tube sheet I2a isillustrated in Fig. 3 and straight fire tubes 28a extended between thetube sheets.

In this modification the superheater I00 is located within the boilershell in close proximity to the rear tube sheet and includes a wrappersheet or shell I82 Which encloses all of the fire tubes and isapproximately elliptical in crosssection to conform with a configurationof the rear tube sheet and the tube group thereat. The superheater isprovided with front and rear superheater tube sheets I04, I06 which arewelded to the shell sheet I02 and through which tube sheets the firetubes pass as heretofore described, the tubes being secured in apressure tight manner in the superheater tube sheets.

The superheater is formed with right and left hand compartments I08, H0by a pair of vertical plates H2, H4 spaced transversely of the boilershell to provide a vertical passage H6 therebetween terminated above thebottom of the superheater shell and also under the top of said shellWhere they are connected with end plates I I8, I that are also connectedwith the wrapper shell I02 to form a steam entrance compartment I22 intowhich saturated steam can flow from a pipe I24, taking steam from thesteam dome I26. Thus saturated steam can flow downwardly between theplates H2, H4 and spread in opposite directions into the lower part ofthe compartments I08, H0. Upwardly inclined vertically spaced partitionplates I28 are located in said compartments and are .welded to thevertical plates H2 or I I4 and the superheater shell I02. Alternateplates are also terminated close to one superheater tube sheet andspaced from the other so as to provide a sinuous passage for steamalternately back and forth horizontally in the line of the fire tubesand progressively upward from the bottom of the compartment to the topthereof Where the steam passes outwardly through separate superheatedsteam pipes I30, I32 and thence in any desired manner to the throttleand locomotive cylinders. The partition plates I 28 also act as staymembers for the elliptical superheater shell. The plates II 2, II 4 aretied together at longitudinally spaced intervals by intervening platesI34 as illustrated in Fig. 5. The lower edges of said plates H2, H4 areterminated upon ribs H5 fixed to and upstanding from the lower part ofthe superheater shell and have depending projections H1 located closebeside and welded to said ribs to ensure a strong connection between thesuperheater shell and said plates.

In the modification illustrated in Figs. 6, '1 and 8, the superheaterI36 is enclosed Within the cylindrical boiler shell I38 of thelocomotive around certain but not the lowermost ones of the first tubesI40 and disposed between the front and rear tube sheets I42, I44 andrelatively close to the rear tube sheet I44. In this modification, thesuperheater comprises the front and rear superheater tube sheets I46,I48 through which the fire tubes pass. Said sheets have circularlyformed ends which confront and are spaced from the interior of theboiler shell and are joined by cylindrically formed shell sheets I50which are spaced from the boiler shell to provide saturated steampassages I52, I54 therebeshell.

tween. Said passages are closed at the ends by plates having arcuatesections I56 interposed between the superheater shell I50 and the boilershell I58 and welded to both. The bottoms of the Passages are closed byplates I64.

The superheater is closed at the top by an upwardly arched plate I58which overlies the tops of the passages I52, I54 and is welded to thesuperheater tube sheets and also to the shell sheets I50 and the boilershell. An opening is formed in the arched plate I58 at the rear part andat each side part thereof registering with the passages I52, I54 andsteam entrance boxes I66, I62 are formed over the openings. Thecylindrical superheater shell sheets are reinforced by arcuate ribs I66located in said passages I52, I54. The arched top closure plate isreinforced by longitudinal ribs I12. The superheater is closed at thebottom by a horizontal closure plate I68.

Saturated steam is taken from the boiler steam dome I14 through amoisture separator I16 from which branch pipes I18 and I conduct thesteam to the separate steam boxes I60, I62. The saturated steam thencefiows through the passages I52, I54 and enters the interior of thesuperheater through longitudinal slots I82 in the bottom part of theshell sections I50. A plurality of Vertically spaced horizontalpartition plates I84 are extended between the tubes and welded to thesuperheater shells. Certain plates have passages I86 through the middlepart thereof, and other alternate plates have passages I88 through sideparts thereof. The arrangement is such that the steam in the lower partof the superheater flows inwardly from the sides to the opening I86 inthe lowermost partition plate, being guided upwardly by the interposedbafile plate I90 and thence in opposite directions transversely of thefire tubes and through the side openings in the next upper partitionplate and so on to the upper part of the superheater where the steamenters the upper compartment I92 under the top plate I58. superheatedsteam is taken from said compartment by pipes I94, I96 opening throughthe top plate at the sides and forward part thereof and passes in anysuitable manner through a superheated steam throttle valve I98, andthence to the locomotive cylinders.

The superheater arrangement illustrated in Figs. 9 through 12, is amodification of that illustrated in Figs. 6, '1 and 8, the superheaterof Figs. 9 through 12 being suspended from instead of being welded, inpart, to the boiler In these figures the superheater 200 comprises adrum having cylindrically shaped outer side sheets 202, and 204 and topand bottom closure sheets 206, 208 of inverted cylindrical shape. Frontand rear superheater tube sheets 2I0, 2I2 are welded to the side and thetop and bottom sheets to form a pressure tight drum and the fire tubes2I4 are extended through the tube sheets as heretofore. The tube sheetshave straight top edges 2I6 so that they upstand above the top sheet 206and form convenient attaching means for hangers 2I8 which at their lowerends are fixed to the upwardly projecting parts of the tube sheets andat their upper parts are attached to brackets 220 fixed to the interiorof the boiler shell 222. The superheater drum thus is suspended from theboiler shell and is spaced from the inner face thereof.

The drum is provided with cylindrical inner side sheets 224, 226 whichconfront and are spaced inwardly from the outer cylindrical sheets 262,264 to provide saturated steam passages 288, 236 therebetween leadingfrom the top to the bottom part of the drum sides. The inner side sheetshave outwardly extended fianges 232, see especially Fig. 12, closelyconfronting but spaced from the tube sheets and welded at their edges tothe outer sheet. The passages are closed at the top and bottom by thetop and bottom sheets 266, 268.

Said inner sheets, at the bottom part thereof, are provided with aseries of vertically elongated and preferably vertically staggered slots209 therethrough through which saturated steam can flow from saidpassages into the interior of the drum and into contact with the firetubes therein.

Saturated steam is admitted into the upper parts of said passages 228,236 through elbows 234, 23$, which are located partly within the drumand have their outlet parts welded in the upper part of the inner sidesheets and their outlet parts extended through and welded in the topsheet 266. Said elbows receive saturated steam through pipes 233, 246connected to a separator 242 located in and receiving saturated steamfrom the steam dome 244 of the boiler shell.

A series of horizontally-disposed vertically spaced partition plates246, 238, 256, 252, 254 are located within the superheater drum as inFig. '7, the plates 246, 250, 254 having apertures 256 in the middleparts thereof and the alternate plates 228, 252 having apertures 258 inthe end parts at the inner side sheets 224, 226. Thus steam isconstrained to flow alternately inwardly and outwardly and progressivelyupward crosswise of the fire tubes and become superheated. Saidpartition plates are preferably welded to the inner side sheets and thusconstitute tie members therebetween but are close to although not fixedrigidly to the tube sheets, as has been explained heretofore.

A baffle sheet 266 is located above the tubes in above the uppermostpartition sheet 254 and is inclined downwardly in both directions fromthe high middle part thereof to guide the superheated steam to fiowrapidly over the fire tubes immediately thereunder to outlets 264, 266opening through the front superheater tube sheet into the uppercompartment of the superheater drum above the top plate 254 and at theside parts of the drum. The superheated steam from the outlets passesinto a single pipe 268 and thence through the throttle 216 to thelocomotive cylinders,

In all of these modifications it is to be noted that the superheatershell surrounds the straight fire tubes and receives heat from thetubes. The superheater is close to the rear tube sheet so that thecombustion gases are highly heated when they are within the superheaterpart of the fire tubes, yet there is a sufficient length of water spacebetween the superheater and the rear tube sheet to reduce the intenseheat of the combustion gases of the fire tube to a lower value that willnot damage the superheater. The superheater thus is protected againstburning out since it is not exposed to the radiant heat of the fire box.

Preferably the length of water evaporating surface of the fire tubesintervening between the rear tube sheet and the superheater is made assmall as is consistent with adequate protection of the superheatingsurfaces against radiation from the fuel bed.

The flow of heat through the heating surface of the boiler as a whole isto a large extent counterflow. Thus the superheater which handles thehottest steam is subjected to the hottest flue gases and the evaporativesurface in front of the superheater which evaporates steam at a lowermean temperature is subjected to the somewhat cooled gases. There is nosurface in the boiler in which the temperature difference is low, andwasted heating surface is therefore avoided.

The superheater at all times is filled with steam under substantiallythe saturated steam pressure except for the slight pressure drop theremay be that is caused by the fiow of steam through the superheater.Thus, the pressure on the superheater shell is small and the shell canbe made of light construction.

Extreme care need not be made in providing joints in the superheaterthat are tight against high pressure because the pressure differencebetween the inside and the outside of the superheater is small.Furthermore, leaks are of minor importance since the steam cannot minglewith the combustion gases to cause corrosion of the parts in contacttherewith.

All superheater headers and special superheater tubes and fiues areeliminated.

The superheater element of the fire tubes is in series with twoevaporating elements. This makes for a larger gas area ince with anysection of the tubes, only two fluids are involved. This feature isimportant as the available gas area which is limited by the boiler shelldiameter limits the size of the locomotive.

We claim:

1. In a locomotive boiler, superimposed communicating large and smallboiler shells, the large boiler shell adapted to contain water to beevaporated into steam and the small boiler shell constituting a steamspace for the large shell, fire tubes in said large shell, a superheaterin said large shell surrounding a part of the length of said fire tubesand providing water evaporating spaces on opposite sides thereof, asaturated steam pipe connecting said steam shell with said superheater,and a superheated steam pipe communicating with said superheater andextended in and lengthwise of said steam shell.

2. In a locomotive boiler, a boiler shell, fire tubes in said shell, asuperheater shell within said boiler shell surrounding a part of thelength of said fire tubes, means providing steam passages between saidboiler shell and superheater shell to the tube collection communicatingwith the lower part of said superheater shell, partition plates withinsaid superheater shell extended crosswise thereof providing steam fiowtransversely of said fire tubes and upwardly therebetween to the upperpart of said superheater shell, and means for conducting superheatedsteam away from said superheater shell.

3. A locomotive boiler comprising a boiler shell, a smaller steam shellon and approximately coextensive with the length of said boiler shelland having communication therewith, a furnace shell having a rear tubesheet located rearwardly of said boiler shell, a front tube sheet, firetubes extended between said tube sheets, said furnace shell including acrown sheet close to the projected top line of the boiler shell, and awrapper sheet about the furnace shell above the crown sheet and abovethe top line of the boiler shell,

and means providing endwise communication be-- tween the steam spaceover said crown sheet and said steam shell.

4. In a boiler, a boiler shell, fire tubes therein, a superheater drumwithin said shell surrounding said fire tubes, said drum including outerand inner spaced sheets confronting the boiler shell providing steampassages opening into the tube space of the drum, means for admittingsaturated steam into said passages, and means for withdrawingsuperheated steam from the tube space of the drum.

5. In a boiler, a boiler shell, fire tubes therein, a superheater drumwithin said shell surrounding said fire tubes, said drum including outerand inner spaced sheets confronting the boiler shell providing steampassages opening into the tube space of the drum, means for admittingsaturated steam into said passages, means for withdrawing superheatedsteam from the tube space of the drum, and means suspending said drumwithin said boiler shell.

6. In a locomotive boiler, a boiler shell, fire tubes in said shell, 2.superheater shell within said boiler shell surrounding a part of thelength of said fire tubes, means providing steam passages between saidboiler shell and superheater shell to the tube collection communicatingwith the lower part of said superheater shell, partition plates withinsaid superheater shell providing steam flow in contact with said firetubes and progressively upwardly therebetween to the upper part of saidsuperheater shell, and means for conducting superheated steam away fromsaid superheater shell.

EUGENE L. SCHELLENS. CHRISTOPHER A. SCHELLENS.

